permanent dipole

[jfontana]

How can I tell which of the following have a permanent dipole but NO Hydrogen bonds?
CH4,  CH3-,  CH3-Br,  NaCl

I think I have eliminated the first 2, but not 100% sure. Thanks

[Chemistry_Guru]

Permanent dipoles occurs when two atoms in a molecule have substantially different electronegativity - one atom attracts electrons more thyan another becoming negative, while the other atom becomes more positive.
whereas hydrogen bond is a type of force that exists between an electronegative atom and hydrogen atom bonded to another electronegative atom ( nitrogen, oxygen or flurine). This type of force involves hydrogen atom.
I hope that helps.